1. Field of the Invention
The present invention relates to an improved structure of electric lock operatable with DC instead of AC, and controlled with a coded chip.
2. Description of the Prior Art
Locks are essential to the protection of human properties, so there have been so many kinds of locks in the market. Among these mechanically operated locks such as cylinder locks and modern electrically operated locks are the most prevailing types.
FIG. 1 is a schematic plane view of a conventional electrically operated lock commonly installed on a door. When the door is closed and in locked state, a tongue piece 11 is projected out, and a latch 12 located at the center thereof is retained by a circular detent washer 13 equipped at the center of a sub-lock case facing against a main lock case so that the latch 12 is captured. When unlocking the lock, by pushing a push button 14, and the latch 12 is released to retreat into the main lock case, thus the door can be opened.
Further detailed construction of a conventional electric lock is shown in FIG. 2. As shown in FIG. 2, two electromagnetic coils 15, 16, an actuated rod 17, a detention arm 18, and a tongue piece operation mechanism 3 are included in the main lock case. The actuated rod 17 is hinged to a pivot axis 171 and laid ahead of the electromagnetic coils 15 and 16 so that it is attracted by the coils 15 and 16 to move horizontally when the coils 15 and 16 are energized. The detention arm 18 approximately disposed perpendicular to the actuated lever 17, is also hinged to a pivot axis 181 and retains the front end of the actuated lever 17 with a jaw formed at its front terminal thereof, while its hinged end at the axis 181 is formed into a recessed breach 182 to trap one side of an inverse U shaped () frame 31 of the tongue piece operation mechanism 3.
The tongue piece operation mechanism 3 is composed of the inverted U-shaped frame 31, the latch 12, the tongue piece 11, a follower member 32 and a connecting rod 33. The inverted U-shaped frame 31 is formed into a narrow slot shape for the latch 12 to tunnel to and fro. The rear portion of the latch 12 is spirally encircled with a coil spring 34 whose one end is secured to the inner side of the rear ledge of the inverted U-shaped frame 31. The front leg of the inverted U-shaped frame 31 stands ahead of the first erecting member 321 of the follower member 32. A second erecting member 322 located behind the first erecting member 321 at a proper distance. The connecting rod 33 tunnels through the two erecting members 321 and 322 and is equipped with a coil spring 331 around its rear portion.
For understanding the operation principle of this lock, reference should be made to FIG. 3. When the lock is in the locked state with is latch 12 retained by the detent washer 13 in the sub-lock case, the  frame 31 exerts a backward pulling force by restoring force of the elongated spring 34. When unlocking, the electromagnetic coils 15, 16 are energized to attract the actuated rod 17 moving horizontally, the detention arm 18 is released to rotate in the counter clockwise direction. At this moment, the  frame 31 retreats backward together with the erecting member 321, follower member 32 and the tongue piece 11 and therefore the unlocking operation is completed. In the unlocked state, the spring 331 is compressed to store energy therein by the retreated tongue piece operation mechanism 3 ready for next coming locking operation.
However, a conventional electric lock constructed as such has the following apparent shortcomings:
1. A considerably strong current is required to attract the actuated rod with a larger torque because the two electromagnetic coils are necessarily installed near the pivoted axis of the actuated rod for operation.
2. Instead of DC, an AC power source is needed to supply such a large current, that necessitates an installation of large and long conductors 36 pulled through the door frame 38 to a power distribution box 37 (see FIG. 4). In this version, the outer appearance of the door frame 38 is spoiled and cost of labor and material is increased by such additional equipment. Besides, peeling of the jacket of the defected conductors 36 may probably lead to an accident.
3. To carry a key along is always bothersome; inadvertent loss of the key may result in loss of property and security as well. A mechanical key is not so dependable as a burglar or any person who happens to pick up the lost key might duplicate it.
In view of the above described shortcomings inherent to the conventional mechanical locks, the inventor of the present invention thus conducted intensive research and experimentation on electric locks. Through years of professional engagement in the manufacturing of related products, the inventor was finally proved to be present a much improved structure of electric lock of the present invention.
One objective of the present invention is to provide an improved structure of electric lock which employs only one electromagnetic coil and a DC power source for operating the lock instead of using two coils and an AC source.
The present invention is also aimed at operating an actuated rod with operating an amplified driving torque produced by the only one coil and a DC power source through elaborate arrangement of mutual positions between a driving rod and the actuated rod.
In addition, the key function of the present invention can controlled by a coded chip attached thereon.
To achieve the above mentioned objectives, the improved structure for electric lock comprises a tongue piece operation mechanism, an actuated rod, a detection arm, an electromagnetic coil and an electric circuit. The tongue piece operation mechanism further includes a tongue piece, a latch, a follower member and a connecting rod. The electromagnetic coil is situated at the same side of tongue piece operation mechanism with a driven rod tunneling through its center thereof. The driving rod is equipped with a spirally coiled spring at its rear end, and its front end is urging the bottom end of the extended portion of the actuated rod so that the electromagnetic coil is able to drive the driven rod to unlock and open the door with internally contained dry battery unit an thus the inconvenience of laying big conductors for AC current is eliminated. Finally, a read head is provided at a proper position in the lock case for reading the chip code of the key before unlocking.